Although warnings are supposed to match brand-name equivalents, researchers found many variations

FRIDAY, Dec. 21 (HealthDay News) -- More than two-thirds of generic drugs in the United States have safety warning labels that differ from the equivalent brand-name drugs, a new study finds.

These labels break U.S. Food and Drug Administration regulations that require generic drugs to carry warnings that are identical to those on brand-name drugs.

Researchers reviewed more than 9,000 product labels for more than 1,500 drugs listed on DailyMed, a website about drug-labeling information that is maintained by the FDA and the U.S. National Library of Medicine.

Of more than 1,000 generic drugs, 68 percent had some discrepancies in their safety labeling. Most had small differences in their labels compared to brand-name drugs, but 9 percent had differences of more than 10 side effects.

Other labeling errors included out-of-date information, incomplete data and, in one case, information for another drug, according to the researchers at the Regenstrief Institute in Indianapolis.

"Physicians frequently use labeling information, either directly or indirectly, to make prescribing decisions. They need to know about side effects, drug interactions and other safety issues," study leader Dr. Jon Duke, assistant professor of medicine at the Indiana University School of Medicine, said in an institute news release.

"We found that generic drug labels may contain incomplete or incorrect safety information," Duke added. "Until this problem is resolved, physicians and patients should rely on brand-drug labeling only, even when the patient is getting a generic version of a drug."

The study was published recently in the journal Pharmacoepidemiology and Drug Safety.

"The solution to the problem of labeling inconsistency may be a centralized listing of drug side effects, maintained independently of individual manufacturer labels," Duke said. "Drug labels would simply reference this common repository rather than attempting to maintain all the information within a single document. Clinicians could refer to this resource for the most up-to-date safety information regardless of generic manufacturer."